SUMMARY

Continuous fiber-reinforced polymer composites (CFRCs) are attractive in structural applications due to their high strength-to-weight ratio. They are composed of a polymer matrix embedded with continuous fibers that are responsible for the majority of load-bearing. Traditional CFRC manufacturing is a tedious process that often requires manual fiber lay-up, which significantly limits the ability to lay fibers in optimal load-bearing directions. Advances in additive manufacturing (AM) have enabled continuous fiber-reinforced variable stiffness composites in which the continuous fibers can follow curvilinear paths, leading to a significantly enlarged design space for CFRCs. To fully exploit such design freedom, fiber layout optimization has been integrated with topology optimization (TopOpt) such that both the macrostructure geometry and the fibers' layout in CFRCs are optimized simultaneously. Nevertheless, AM technologies for CFRCs have limitations and existing TopOpt formulations for designing CFRCs lack the manufacturing constraints needed to ensure manufacturability. In an effort to balance structural performance and manufacturability, the proposed research aims to develop a framework to effectively design CFRCs with TopOpt, which are manufacturable by AM. Three specific research questions will be investigated.
1. How well do toolpaths generated from a discrete vector field describing optimized fiber orientations balance structural performance and manufacturability of CFRCs, when generated using existing streamline and projection-based methods?
2. How can “CFRC constraints” be integrated directly into a TopOpt formulation to arrive at a vector field describing optimized fiber orientations such that when post-processed via an existing toolpath generation method, we arrive at designs that most effectively balance structural performance and manufacturability?
3. Can “as-built” mechanical properties of the CFRCs be considered during optimization by generating
toolpaths from the discrete vector field, and if so, how do the results compare to the post-processing approach in terms of structural performance, manufacturability, and computational cost?
The proposed research will lead to an effective framework to design and manufacture optimized CFRCs that can be tuned to a particular AM platform. The scientific and engineering outcomes will aid both the design and manufacturing of CFRCs for conventional use in industry.